The present invention relates to a method and apparatus for orienting a device axis in a defined state.
The accuracy of equipment, such as rotating lasers, is affected by ambient conditions, such as the storage temperature or operating temperature of the apparatus, by an external force on the apparatus in the event of falls or heavy impact, and by aging processes of the apparatus components of the apparatus. The aging of the device components takes place on a long time scale and changes the accuracy of an apparatus very slowly. The external impact on an apparatus by a fall or a strong impact is an event that is unpredictable to the operator and therefore difficult to take into account. By contrast, the operating temperature of an apparatus is a quantity that always affects the accuracy of the apparatus. Every use or operation of the apparatus is subject to environmental conditions which influence the accuracy of the apparatus.
Rotating lasers can be arranged in different device layers, which are arranged as horizontal position and vertical position. In this case, a distinction is made between horizontally usable rotating lasers, which are used exclusively in the horizontal position, and horizontally and vertically usable rotating lasers, which are used in horizontal position and vertical position. Horizontally usable rotating lasers have as device axes on a first horizontal axis and a second horizontal axis, which are perpendicular to each other and span a horizontal plane. Horizontally and vertically usable rotating lasers have as a device axis in addition to the first and second horizontal axis on a vertical axis which is perpendicular to the horizontal plane of the first and second horizontal axis.
In their operating instructions, for the operating temperature of the rotating laser the device manufacturers of rotating lasers define a temperature range in which the rotating laser may be operated. The operation of rotating lasers is typically allowed in a temperature range of −20° C. to +50° C. The adjustment of a rotating laser and the calibration of the device axes are carried out by the device manufacturer under fixed environmental conditions; the calibration of the device axes is typically carried out at a normal temperature of +20° C. In order to ensure the accuracy of a rotating laser during operation, the accuracy must be regularly checked by the operator and a calibration of the rotating laser must be carried out if a maximum difference, which has been defined by the device manufacturer, is exceeded. The accuracy of the rotating laser for each device axis is checked separately.
Methods are known for checking and/or calibrating a horizontal axis, which are used in all horizontally applicable rotating lasers, and for checking and/or calibrating a vertical axis, which are used exclusively in vertically usable rotating lasers. In a first method, the first horizontal axis is checked and in a second method the second horizontal axis is checked, wherein the order in which the first and second methods are performed is arbitrary. In the case of horizontally and vertically usable rotating lasers, following the check of the first and second horizontal axes, the vertical axis is checked in a third method.
The orientation of the device axes in a defined state is done by means of a leveling device, which is arranged in a device housing of the rotating laser. The defined state of the device axes may be a horizontal state or a vertical state. The leveling device comprises a first leveling unit, which orients the first horizontal axis in a first defined state, a second leveling unit, which orients the second horizontal axis in a second defined state, and in a vertically insertable rotating laser, a third leveling unit, which orients the vertical axis in a third defined state. The leveling units each comprise a tilt sensor which measures the tilt of the device axis, and an adjusting element with which the tilt of the device axis is adjustable. Ideally, the tilt sensors are oriented parallel to the assigned device axes. If a tilt sensor is not oriented parallel to the assigned axis of the device, the axis of the device has a tilt error.
For horizontal or vertical orientation of equipment such as rotating lasers, spirit levels are usually used as tilt sensors. A tilt sensor formed as a spirit level comprises a housing filled with a liquid and a gas bubble, a light source, and one or more photodetectors. The housing is closed by a convexly curved cover layer and the gas bubble moves along the cover layer when the tilt sensor is tilted with respect to a horizontal or vertical reference plane. The light source preferably emits divergent light (e.g., LED) and is centered with an optical axis of the tilt sensor, which simultaneously forms the axis of symmetry of the spirit level. The gas bubble in the sealed liquid indicates the orientation of the bubble. The gas bubble is always at the highest point of the liquid. The spirit level is connected to the apparatus so that the gas bubble is in the defined state of the apparatus at a certain point of the spirit level. The defined state of the apparatus can be made or restored with the help of the spirit level with little effort. The defined state does not necessarily have to be a horizontally or vertically oriented state of the apparatus. In principle, any desired tilted arrangement for the defined state can also be predetermined by a tilted arrangement of the bubble level on the apparatus.
Known rotating lasers, such as the Laser Beacon LB-400 rotating laser, have a temperature sensor that measures the temperature inside the device housing of the rotating laser. If the measured temperature exceeds the upper limit of the permissible temperature range during operation, the operation of the rotating laser is interrupted by switching off the motors and the beam source. Once the measured temperature falls below the upper limit, the operation of the rotating laser can be continued. The temperature sensor ensures that the motors and the beam source are operated only within the allowable temperature range and protects these device components from damage due to increased temperatures. The temperature of the rotating laser is not taken into account when calibrating the device axes of the rotating laser.
From DE 10 2013 217 479 A1 a rotating laser is known in which the influence of the temperature, the influence of accelerations or forces acting on the rotating laser and the aging of the device components of the rotating laser are taken into account. The rotating laser comprises a monitoring unit and a sensor unit with a temperature sensor, an acceleration sensor and a real-time sensor. The temperature sensor measures a storage or operating temperature of the rotating laser, the acceleration sensor measures occurring forces and accelerations from falls or high impact, and the real-time sensor measures the time since the last proper calibration of the rotating laser. The measured values of the sensors are recorded at regular intervals with the aid of the monitoring unit and forwarded to a control and evaluation device. Limit values are defined for each measurand and the measured values of the sensors are compared with the limit values. If a measurand is outside the limit value, a warning is generated for the operator with the aid of the monitoring unit. The warning message is visually or acoustically displayed and includes a prompt for the operator to calibrate the rotating laser. For the measurand “temperature,” a limit interval is defined with a lower limit and an upper limit, the lower limit being the minimum temperature and the upper limit being the maximum temperature of the allowable temperature range. For the measurands “acceleration” and “time duration,” upper limit values are defined.
The method for orientation of a device axis known from DE 10 2013 217 479 A1 has the disadvantage that the temperature sensor can be attached to any position in the device housing of the rotating laser. DE 10 2013 217 479 A1 makes no statements about the type of temperature sensor and the spatial arrangement of the temperature sensor in the device housing of the rotating laser. In rotating lasers which are used outdoors, temperature differences within the rotating laser can occur due to solar radiation. In this case, the temperatures in regions of the rotating laser with direct solar radiation can differ by several degrees Celsius from temperatures in shaded areas, and the measured temperature is dependent on the spatial arrangement of the temperature sensor in the device housing of the rotating laser. The measured temperature is not taken into account when calibrating the device axes of the rotating laser and only represents a criterion when calibration of the device axes of the rotating laser is required.
The object of the present invention is to develop a method for orientation of a device axis in a defined state, in which the operating temperature of the apparatus is taken into account when orienting the device axis.
According to the invention, the method for orienting a device axis in a defined state comprises the following steps:                Storing a curve of zero positions of a tilt sensor of a leveling unit as a function of an operating temperature of the apparatus or of an operating temperature-dependent measurand in a control device,        Measuring the operating temperature or the measurand,        Determining the associated zero position of the tilt sensor to the measured operating temperature or measurand based on the characteristic curve and        Orienting the device axis in the defined state by means of the leveling unit, which is determined by the derived zero position of the characteristic curve.        
The method according to the invention for orienting a device axis in a defined state has the advantage that the operating temperature of the apparatus is taken into account when orienting the device axis in the defined state and the temperature dependence of the zero position of the tilt sensor is eliminated. The operating temperature of the apparatus is the temperature which occurs during operation of the apparatus. The operating temperature is measured inside the device housing of the apparatus using a temperature sensor or the operating temperature is determined by a measurand that is dependent on the operating temperature. The defined state, in which the device axis of the apparatus is oriented by means of the leveling unit, may be a horizontal state, a vertical state or a tilted state of the device axis. The characteristic curve stored in the control device of the apparatus establishes a relationship between the operating temperature or the measurand and the temperature-dependent zero position of the tilt sensor for the device axis. As a zero position of the tilt sensor, the tilt angle is defined, which corresponds to the defined state of the device axis. From the characteristic curve, a zero position can be read for each operating temperature from the permitted operating temperature range. In the characteristic curve, a distinction can be made between temperatures at which the device axis was calibrated and temperatures at which no calibration of the device axis has yet been made.
The method according to the invention can also be carried out with a measurand that is dependent on the operating temperature. In this case, it is not the operating temperature of the apparatus which is measured, but the temperature-dependent measurand. Suitable parameters for the method according to the invention are temperature-dependent values of the apparatus, whose temperature dependence is known. The measurement of a measurand that is dependent on the operating temperature is appropriate when a measurand is used which is already measured for other purposes, so that no additional measurement effort exists, or if a measurand is used that can be measured with existing sensor elements so that there is no additional expenditure on equipment. The gas bubble of the tilt sensor has a bubble length, which is temperature-dependent and is therefore suitable as a measure of the operating temperature. The bubble length can be measured by means of the light source and the photodetector of the tilt sensor, so that no further sensor element is required for the measurement.
Preferably, the operating temperature of the apparatus is measured by means of the tilt sensor comprising a housing filled with a liquid and a gas bubble, a light source and at least one photodetector. The measurement of the operating temperature of the apparatus by means of the tilt sensor has the advantage that the operating temperature is measured exactly at the location in the device housing of the apparatus, which is relevant for the orientation of the device axis. The temperature measurement is carried out with the aid of the components of the tilt sensor, so that no further sensor element is required and the apparatus required for the temperature measurement is low.
A further characteristic curve of operating temperatures and bubble lengths of the gas bubble is particularly preferably stored in the control device, the bubble length of the gas bubble is measured by means of the light source and the photodetector of the tilt sensor and the operating temperature associated with the measured bubble length is determined on the basis of the further characteristic curve. The tilt sensor of the leveling unit comprises a housing filled with a liquid and a gas bubble, a light source and one or more photodetectors. The gas bubble of the tilt sensor has a bubble length, which is temperature-dependent and is therefore suitable as a measure of the operating temperature. The bubble length can be measured by means of the light source and the photodetector of the tilt sensor, so that no further sensor element for the temperature measurement is required.
In a further development of the method according to the invention, the accuracy with which the device axis of the apparatus is oriented in the defined state by means of the leveling unit is checked during operation of the apparatus by means of a fixed test loop, wherein a deviation from the defined state of the instrument axis is determined and compared with a maximum deviation. The device manufacturer specifies a maximum deviation for the device axis of the apparatus. As long as the deviation from the defined state of the device axis is less than the maximum deviation, the apparatus can, with proper use, be used with the accuracy specified by the device manufacturer. If the deviation from the defined state of the device axis is greater than the maximum deviation, the accuracy of the apparatus specified by the device manufacturer is not met despite proper use and the device axis must be calibrated, taking the operating temperature into account when calibrating the device axis. The test loop differs in horizontal axes and vertical axes. If the device axis is formed as a horizontal axis, a method for checking a horizontal axis is performed; if the device axis is formed as a vertical axis, a method for checking a vertical axis is performed.
If the deviation from the defined state of the device axis is greater than the maximum deviation, a new zero position of the tilt sensor for the defined state of the device axis is calculated and the characteristic curve of zero position and temperature or zero position and measurand is updated. In order to improve the accuracy of the apparatus, the operator performs a calibration of the instrument axis and determines a new zero position of the tilt sensor for the defined state of the device axis. This new zero position is used to update the characteristic curve stored in the control device.
The further method steps of the method according to the invention depend on whether the characteristic curve stored in the control device for the measured operating temperature or measurand has a stored zero position of the tilt sensor for the defined state of the device axis. The device manufacturer of the apparatus defines a temperature range for the operating temperature of the apparatus and calibrates the instrument axis at an operating temperature or at several operating temperatures. The measured zero position of the tilt sensor for the defined state of the device axis is stored together with the temperature or measurand as a value pair. The accuracy of the equipment increases with the number of different operating temperatures or measurands for which calibration of the device axis has been performed. For each temperature in the operating temperature range of the apparatus can be determined from the characteristic curve of a zero position, which is used for the orientation of the device axis in the defined state. A distinction is made between temperatures at which the device axis was calibrated and temperatures at which no calibration of the device axis has yet been performed. For the temperatures in the operating temperature range for which no calibration of the device axis has been carried out, interpolation takes place from the stored zero positions.
If the characteristic curve for the measured operating temperature or measurand has a stored zero position, the stored zero position of the tilt sensor for the defined state of the device axis in the characteristic curve is replaced by the new zero position. In this case, an old value pair in the characteristic curve is replaced by a new value pair, wherein the new value pair can also change the interpolated zero positions. The accuracy of the equipment increases with the number of different operating temperatures or metrics for which the device manufacturer has calibrated the device axis.
If the characteristic curve has no stored zero position of the tilt sensor for the measured operating temperature or measurand, a new value pair of zero position and temperature or measurand is added to the characteristic curve. With each value pair, which is supplemented in the characteristic curve, the accuracy of the apparatus grows.
In a preferred embodiment, the manufacturer stores the characteristic curve over a temperature range between a lower temperature and an upper temperature in the control device in the delivered state of the apparatus, the characteristic curve having at least two value pairs of zero positions of the tilt sensor for the defined state of the device axis and temperatures or measurands. The accuracy of the equipment increases with the number of different operating temperatures or metrics for which the device manufacturer has calibrated the device axis.
The apparatus is characterized according to invention in that in the control device, a characteristic curve is provided which represents a zero position of the tilt sensor for the defined state of the device axis that is dependent on the operating temperature of the apparatus or dependent on the operating temperature measurement. The characteristic curve establishes a relationship between the operating temperature or measurand and the temperature-dependent zero position of the tilt sensor for the device axis of the apparatus. From the characteristic curve, a zero position of the tilt sensor can be read for each temperature from the permitted operating temperature range. The accuracy with which the apparatus is operated can be increased by the use of a temperature-dependent zero position of the tilt sensor. A calibration of the device axis is only required if the orientation of the device axis has been changed by an external force or by aging of the device components.
Preferably, a further characteristic curve is provided in the control device, which represents the operating temperature of the apparatus as a function of a bubble length of the gas bubble of the tilt sensor. The tilt sensor includes a housing filled with a liquid and a gas bubble, a light source, and one or more photodetectors. The gas bubble of the tilt sensor has a bubble length, which is temperature-dependent and is therefore suitable as a measure of the operating temperature. The bubble length of the gas bubble can be measured with the aid of the light source and the photodetector, so that no further sensor element for the temperature measurement is required. In addition, the operating temperature is measured exactly at the location in the equipment housing of the apparatus that is relevant to the orientation of the device axis.
In a preferred further development, the apparatus has a first device axis, which can be oriented in a first defined state by means of a first tilt sensor and a first adjustment element, and a second device axis, which can be oriented by means of a second tilt sensor and a second adjustment element into a second defined state, and a first characteristic curve and second characteristic curve are provided in the control unit, wherein the first characteristic curve represents a first zero position of the first device axis in the first defined state as a function of the operating temperature of the apparatus or the measurand that is dependent on the operating temperature, and the second characteristic curve represents a second zero position of the second device axis in the second defined state depending on the operating temperature of the apparatus or the measurand as a function of the operating temperature. The advantage of the apparatus according to the invention is that a separate characteristic curve is stored in the control device for each device axis of the apparatus, which represents the dependence of the zero position of the tilt sensor on the operating temperature or the measurand. The apparatus has a first and a second axis of the device, which can be oriented with the aid of a first and second leveling unit in a defined state. The first leveling unit comprises a first tilt sensor and a first adjusting element and the second leveling unit comprises a second tilt sensor and a second adjusting element.
Particularly preferably, a further first characteristic curve and a further second characteristic curve are provided in the control device, the further first characteristic curve representing a first temperature of a first tilt sensor as a function of a first bubble length of a first gas bubble and the further second characteristic curve representing a second temperature of a second tilt sensor dependent on a second bubble length of a second gas bubble. The advantage is in the fact that the control unit for each device axis of the apparatus stores its own additional characteristic curve, which represents the dependence of the bubble length of a gas bubble on the temperature. The first tilt sensor has a first gas bubble and the second tilt sensor has a second gas bubble. The first gas bubble of the first tilt sensor has a first bubble length, which is temperature-dependent and is therefore suitable as a measurand for the first temperature of the first tilt sensor. The second gas bubble of the second tilt sensor has a second bubble length, which is temperature-dependent and is therefore suitable as a measurand for the second temperature of the second tilt sensor.
The first and second tilt sensors are arranged in different areas of the device housing of the apparatus and can be exposed to different temperatures. The use of the tilt sensors as temperature sensors has the advantage that the temperatures in the areas in the device housing of the apparatus are measured, which are relevant for the orientation of the device axes. The dependence of the bubble length of the gas bubble on the temperature can also differ from each other with tilt sensors of the same sensor type and/or the same series. If a separate characteristic curve is created for each tilt sensor, the accuracy with which the equipment is operated can be increased.
Embodiments of the invention are described below with reference to the drawings. This is not intended to illustrate the exemplary embodiments on the basis of a scale, but the drawings are executed schematically and/or slightly distorted. It should be understood that various modifications and changes in the form and detail of an embodiment may be made without departing from the general idea of the invention. The general idea of the invention is not limited to the exact form or detail of the preferred embodiment shown and described below, or is limited to an object which would be limited in comparison to the subject matter asserted in the claims. In the case of given design ranges, values within the limits mentioned are also to be disclosed as limiting values and can be used and claimed as desired. For the sake of simplicity, reference numerals are subsequently used below for identical or similar parts or parts with the same or similar function.